Rebels fighting Col Gaddafi's forces fear that a no-fly zone or other assistance from the outside world will come too late.

Government forces continued to bombard opposition positions, including with air strikes, rebel forces said, though attacks were hindered by a sandstorm over the town of Ajdabiya, the new main front line.

If they take Ajdabiya, they can choose whether to move straight on Benghazi, the rebels' capital, or take the main road to Tobruk and the border with Egypt, cutting off the rebels and surrounding them.

"Everyone here is puzzled as to how many casualties the international community judges to be enough for them to help. Maybe we should start committing suicide to reach the required number," the rebel spokesman, Essam Gheriani, said in Benghazi.

A number of missiles landed west of Ajdabiya but by nightfall there had been no assault on the town itself. Rebels claimed still to be fighting in the oil terminal town of Brega, further east, which the government claimed to have taken on Sunday.

In the west, government forces moved in to retake the small town of Zwara, a rebel holdout. Residents told reporters that a number had been killed as tanks moved into the town square.

Related Articles

Zuwara is to the west of Zawiyah, the town which has seen the fiercest fighting. It took the government several days of repeated tank attacks to subdue the rebels.

The town remains cut off from the outside world, though one activist in exile, Hassan El-Amin, said he had been told the army were still suffering night-time attacks.

Libya's third-largest city, Misurata, 125 miles to the east of Tripoli, remains securely in rebel hands, though doctors are reporting shortage of medical supplies owing to an effective siege. Mr El-Amin said some had made it through by sea, despite a blockade by the government.

Khalid, an activist still in Misurata, said there had been no attack on the city in recent days, something residents link to claims of fighting within the army base at the city's airport outside town.

The claims cannot be verified, but residents say that after 32 soldiers defected from the base to the city, there was heavy shooting heard from the base, which they attributed to a clash between the elite Khamis Brigade and the locally based Hamza Brigade, which had refused orders to join battle.

"We have no other explanation," Khalid told The Daily Telegraph. "Hamza Brigade members have assured people by telephone that many soldiers are refusing orders."

The claims of mutiny were dismissed on Sunday night by a military spokesman, Col Milad Hussein, as "propaganda".